Emily Parker spoke with author Alister McGrath about his latest book, 'The Great Mystery.'

These are really big questions and social psychologists are very good at helping us to see that they matter to people.

In my own case, I'm a Christian and I'm very comfortable in my faith. Although many years ago I was an atheist who found his way to faith, actually for me Christianity gives very good answers to those questions, ones that I find deeply satisfying. It gives me this sense of who I am and what life is all about and we all need something like that if are going to live meaningful lives in this world.

Emily: How did you become a Christian?

Alister: I went to Oxford University to study science and I expected that to confirm my atheism. In fact it didn't. It opened up some new questions. It made me realise that atheism was not as robust, or straight forward, as I'd thought. Also I began to realise that Christianity was something much more exciting than I had realised. I was beginning to lose faith in my atheism and beginning to realise that Christianity seemed very exciting. So, if you like, I left behind one faith and took on another.

I know some people will say, 'is atheism a faith?' Well, I think it is. As an atheist I believed there was no god; as a Christian I believe there is a God. So in many ways I'd moved from one faith position to another and I'm very happy where I am now.

Emily: In your book you say that there are times when we ask the questions, but there are also some questions we're not necessarily going to get all the answers for right there and then. For some people it might be seen as being lazy, accepting the fact that we might not get all the answers in the way that we want to. What's your perspective on this?

Alister: I would understand that position. It does sound a bit lazy, but when you think about it a bit more, you begin to realise that some of these questions are just so big and complex, that the kind of answers we might give don't really do justice to them.

My own feeling is we can learn to live with some questions. In other words not necessarily being able to see the full detail of everything, nevertheless seeing enough to let us say, "That's right, that makes sense." In the New Testament for example, Paul very often talks about walking by faith and not by sight. All Paul was getting at really was that we don't see things with absolute clarity, but we do see them well enough to enable us to work out what's going on and to live a meaningful life.

Emily: When we begin to ask these questions, is there a freedom that comes?

Allister: We must feel free to ask these questions. When I was an atheist, I began to ask certain very deep questions and realised atheism did not give good answers. I think Christians in particular mustn't be frightened about asking these questions, or indeed encouraging their friends to think about them; because very often when people begin to open up really big questions, they begin to realise that maybe the answers they have found thus far aren't good enough. That's very important. It's a bit like opening a door and realising there is a wonderful new world beyond what we presently know and it's asking us to go in and discover it.

Emily: We've seen in society the likes of CS Lewis and JR Tolkien who have brought the Narnias and The Lord of the Rings trilogies. Do you think books like these make a real difference to our quest to ask some of those questions?

Allister: Both Lewis and Tolkien in their own ways help us to have confidence to ask those questions. Certainly if you look at Tolkien's Lord of the Rings trilogy, he is asking very deep questions. What is virtue? How do we live a good life? What is the bigger picture of what we are part of? Do the little people just get squashed by everybody else or do they really matter?

Lewis in Narnia is asking some even bigger questions: What stories can we trust as we walk our way through life?

Both Lewis and Tolkien help us to realise that you cannot evade these big questions. They help us to see they're there, they matter, and I think in many ways they're saying to us, be brave, begin to think about these questions and realise that in both our cases, Christianity gives some very good answers that most of us, I'm afraid haven't really thought about enough.